bug#47300: delete-window to select window with same position

[martin rudalics]

> The customization interface could use only functions that could be
> first called before deletion, then the customized function returns
> a lambda that will be called after deletion.

Only specialized users would be able to write such a function. And they
can use the 'delete-window' parameter for that purpose.

> Then for example
> all 'pos' logic could be moved to a separate function:
>
> (defun delete-window-pos ()
>    (let ((frame-selected-window-edges (window-edges frame-selected-window nil 
nil t))
>          (frame-selected-window-pos (nth 2 (posn-at-point nil 
frame-selected-window))))
>      (lambda ()
>        (let ((new-frame-selected-window
>         (window-at-pos
>                (+ (nth 0 frame-selected-window-edges)
>                   (car frame-selected-window-pos))
>                (+ (nth 1 frame-selected-window-edges)
>                   (cdr frame-selected-window-pos))
>                frame t)))
>          (and new-frame-selected-window
>               ;; Select window at WINDOW's position at point.
>         (set-frame-selected-window
>                frame new-frame-selected-window))))))

I'm completely lost with the scoping of that first `let'.  So at least
for a poor soul like me such a solution would not be feasible at all.

martin